Animal models allowing investigation of the function of adhesion molecules in transfusion biology are one of the central themes of this program. Without any doubt the technology of genetic engineering of animals is one of the greatest advances in biology in recent years. Unfortunately, animal experimentation is not simple. In particular, there is variability: genetically engineered animals are not truly clones of each other and therefore their responses to treatment may differ. This is especially the case if the mice are of mixed background and not fully backcrossed to a particular genetic background. To minimize variability, wild-type animals are used from the same heterozygous matings to have litter mates comparisons or at least from the same animal colony. Therefore, often both mutant and wild-type animals have to be housed. So in addition to the mutant strains listed in Table 1, there are several wild-type strains that we need to keep. To obtain statistically meaningful results, each experiment has to involve a minimum of 6-10 animals of each genotype. The cost of animal housing is becoming prohibitive. This core unit is one of the reasons why this program was originally put together. To be able to maintain and breed a large number of mice of a certain genotype for experimental purposes, a mouse colony consisting of three breeding cages (to maintain the line) plus additional breeding and experimental cages (for expansion) is needed. In our experience a good ratio of breeding cages to experimental cages in the expansion colony is 1:6, commonly resulting in a colony of more than 50 cages. As Table 1 clearly shows this many colonies could not be established by each individual investigator and many mouse lines listed will be used in two or more different laboratories. Therefore, Stephen Cifuni, the animal technologist who will direct the mouse husbandry will be able to coordinate production of pups of one genotype for several laboratories in parallel. Working as a group will also minimize losses. Some experimental designs require a particular sex of the animals. The litter mates of the opposite sex will then most likely find use in another study at a different laboratory and will not have to be sacrificed. As the program developed and the projects expanded in their use of mice it became clear that not all mice now needed for Project 2 (Hartwig) and 4 (Silberstein) could be housed at CBRI. Therefore only their mice that will be used collaboratively at CBRI for imaging purposes, thrombus formation studies, platelet clearance, homing experiments etc will be housed within CBRI while the rest of the mice required for non -collaborative studies for these two projects will be housed in their own in-house facilities under subcontracts. The Core will continue to maintain strains that are used more rarely for all 4 projects. Mice produced at CBRI are easily transferred to the other institutions using the CBRI van and for this we keep a valid health certificate for our animals always on file. Dr. Wagner's laboratory members have trained a technologist, Stephen Cifuni, B.S. in Biology, Boston College, 2004. Mr. Cifuni has been employed at the Center for Blood Research for several months and has already been part of this program. He will now be directing the animal work in Core B. He is fully capable of managing the animal colonies that will continue to be part of this Core B. His duties are and continue to be the following 1) Check all cages first thing in the morning for water and food supplies, cleanliness and health of the animals. Correct all observed problems immediately and speak to care givers as necessary. 2) Mark cages that require veterinary attention with red cards and contact the veterinary consultant, Dr. Garibaldi, if necessary. 3) Make autopsies on dead animals and collect blood samples from sick animals for analysis. Have a kit ready to make cultures and be a veterinary helper as needed. 4) Send out sentinel animals and keep records. 5) Set up breedings on request and transport animals to laboratories. CBRI has a van that can be used if laboratory is located in another building. 6) Keep computerized records of all breedings and of all housed animals for every genotype. 7) Instruct all new program personnel on procedures and rules of the mouse facility - including the immuno-deficient room. 8) Keep records on budgetary issues, so that no group overspends the amount allocated to their project. 9) Actively participate in the Animal Care and Use Committee at CBRI, writing and reviewing animal protocols in particular those needed for this Program. Mr. Cifuni is also trained in special animal procedures such as retro-orbital bleeding;tailing mice for genotyping;PCR and Southern analysis of tail DNA;fixing tissues for histology;tail vein injections;etc. He is able to teach other members of the program these procedures